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  • 1. Bosiljevac, M.
    et al.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Sipus, Z.
    Hybrid spectral domain - UTD method applied to conformal antenna analysis2006In: Eur Space Agency Spec Publ ESA SP, 2006Conference paper (Refereed)
    Abstract [en]

    A hybrid spectral domain - UTD method (Uniform Theory of Diffraction) developed for the analysis of conformal antennas is presented in this paper. The basic idea behind the hybrid method is to combine different analysis methods for conformal antennas and, at the same time, preserve the advantages of the considered methods. More specifically, the considered hybrid SD - UTD method joins the possibility of analyzing multilayer structures (spectral domain method) and the possibility of analyzing electrically large structures (UTD method). Hence, using the developed method it is possible to analyze large multilayered conformal antennas with high accuracy and speed. This work has been made possible by the ACE program for structuring the research on conformal antennas in Europe. The developed method is a result of joining research activities of University of Zagreb, Croatia and the Royal Institute of Technology, Sweden.

  • 2. Bosiljevac, Marko
    et al.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Sipus, Zvonimir
    Efficient Analysis of Aperture Antennas on Generally Shaped Convex Multilayered Surfaces Using a Hybrid SD-UTD Method2009In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 57, no 5, p. 1420-1431Article in journal (Refereed)
    Abstract [en]

    A novel hybrid method is described for analyzing convex multilayered conformal array antennas. The hybrid method is based on the spectral domain approach in combination with the ray-based uniform theory of diffraction (UTD) method. The analysis is divided in two parts. First, the spectral domain approach is accelerated by using an asymptotic extraction technique where the extracted term of the Green's function is calculated using UTD. It is shown that this new approach results in significant acceleration of the existing spectral domain algorithm without losing accuracy. The modified spectral domain method is then used in the second part where generally shaped convex multilayered surfaces are analyzed by using sets of canonically shaped surfaces (spheres and/or circular cylinders). Their radii are obtained using the UTD formulation, which contains important information such as distance and curvature of the generally shaped surface along each geodesic. The results obtained using the new algorithm are compared to the available results (calculated and measured) for different conformal antennas, showing very good agreement.

  • 3.
    Ellgardt, Anders
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Characteristics of a broad-band wide-scan fragmented aperture phased array antenna2006Conference paper (Refereed)
    Abstract [en]

    In this paper a phased array antenna is described that is designed with the help of a genetic algorithm for scan angles out to 60° from broadside. The focus is on simplifying the manufacturing of the diagonally adjoining pixels and on numerical results for thin antennas. The effects of the corner to corner contacts are studied and results for two synthesized elements ar Test and measurement requirements on wireless devices

  • 4. Josefsson, L.
    et al.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Conformal Array Antenna Theory and Design2006Book (Other academic)
    Abstract [en]

    This is the first comprehensive treatment of conformal antenna arrays from an engineering perspective. While providing a thorough foundation in theory, the authors of this publication provide a wealth of hands-on instruction for practical analysis and design of conformal antenna arrays. Thus, you get the knowledge you need, alongside the practical know-how to design antennas that are integrated into such structures aircrafts or skyscrapers.

  • 5. Josefsson, L
    et al.
    Persson, Patrik
    KTH, Superseded Departments, Electromagnetic Theory.
    Conformal array synthesis including mutual coupling1999In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 35, no 8, p. 625-627Article in journal (Refereed)
    Abstract [en]

    A pattern synthesis technique for a conformal array antenna on a cylinder is presented using the method of alternate projections. Both the sidelobe region and the shape of the main beam are controlled. The method includes the effect of the mutual coupling in the synthesis. It is shown that if mutual coupling is neglected, then poor results are obtained, especially in the shaped beam region.

  • 6.
    Persson, Patrik
    KTH, Superseded Departments, Electromagnetic Theory.
    Analysis and Design of Conformal Array Antennas2002Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Today there is a great need for communication between people and even between things, using systems onboard e.g. aircraft, cars, ships and satellites. As a consequence, these communications needs require antennas mounted on or integrated in the surfaces of different vehicles or platforms, i.e. conformal antennas. In order to ensure proper operation of the communication systems it is important to be able to determine the characteristics of these antennas. This thesis is about the analysis and design of conformal antennas using high frequency asymptotic methods. Commonly used eigenfunction solutions or numerical methods such as FDTD, FEM or MoM are difficult to use for arbitrarily shaped electrically large surfaces. However, the high frequency approximation approach together with an accurate ray tracing procedure offers a convenient solution for these surfaces. The geodesics (ray paths) on the surfaces are key parameters in the analysis and they are discussed in detail. In the first part of the thesis singly and doubly curved perfectly electrical conducting (PEC) surfaces are studied, with respect to the mutual coupling among aperture type elements. A synthesis problem is also considered where the effect of the mutual coupling is taken into account. As expected, the mutual coupling must be included in the synthesis procedure to be able to realize the prescribed pattern, especially in the shaped main lobe. Furthermore, the polarization of the antenna elements is very important when considering antennas on generally shaped surfaces. For such antennas the polarization must most likely be controlled in some way for a proper function. For verification of the results two experimental antennas were built at Ericsson Microwave Systems AB, Mölndal, Sweden. The first antenna is a circular cylinder with an array of rectangular waveguide fed apertures and the second antenna is a doubly curved surface (paraboloid) with circular waveguide fed apertures. It is found that it is possible to obtain very accurate results with the asymptotic method when it is combined with the Method of Moments, i.e. a hybrid method is used. The agreement compared to measurements is good at levels as low as –80 dB in many cases. The second part of the thesis is about the development of a high frequency approximation for surface field calculations on a dielectric covered PEC circular cylinder. When using conformal antennas in practice they have to be covered with a radome for protection and with the method developed here this cover can be included in the analysis. The method is a combination of two different solutions, one valid in the non-paraxial region of the cylinder and the other is valid in the paraxial region. The method is verified against measurements and reference results obtained from a spectral domain moment method code.

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  • 7.
    Persson, Patrik
    KTH, Superseded Departments, Electromagnetic Theory.
    Calculating Geodesics on Doubly Curved Surfaces: The case of a General Paraboloid of Revolution2000Report (Other academic)
  • 8.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Fourth European Workshop on Conformal Antennas2005In: IEEE Antennas & Propagation Magazine, ISSN 1045-9243, E-ISSN 1558-4143, Vol. 47, no 3, p. 123-124Article in journal (Refereed)
    Abstract [en]

    The fourth European workshop on conformal antennas (ECWA '05) took place in Stockholm, Sweden. The session started with a focus on three major topics. The first of which was an overview of conformal array antenna (CAA) research in Japan. Second was the discussion of two types of pattern-synthesis methods namely: the projection method, and the null-point adjusting method. Lastly, calibration methods for conformal array antennas were discussed. The remaining papers were divided into five sessions, of which two sessions were devoted to modeling techniques and three sessions were about antenna characteristics and applications. A design and development of a conformal radar demonstrator and a faceted cylindrical array antenna demonstrator were among the highlights that were presented. The second and last day saw several technical meetings, one of which was a working meeting for the conformal antenna work package within the Antenna Center of Excellence (ACE).

  • 9.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Modeling Conformal array antennas of various shapes using Uniform Theory of Diffraction (UTD)2006In: Applied Computational Electromagnetics Society Journal, ISSN 1054-4887, Vol. 21, no 3, p. 305-317Article in journal (Refereed)
    Abstract [en]

    Traditionally, antennas have been designed as separate components, mounted on e.g. masts, buildings, and vehicles. Modem systems, however, require antennas to be integrated with existing structures. This paper discusses the analysis of conformally integrated array antennas using the hybrid UTD-MoM method, in particular arrays on doubly curved surfaces. Computed results are shown including singly and doubly curved surfaces. Most of the results are verified by measured results and calculated results obtained with a modal solution.

  • 10.
    Persson, Patrik
    KTH, Superseded Departments, Electromagnetic Theory.
    The Mutual Coupling between Apertures on Convex Cylinders1999In: Proceedings of radiovetenskap och kommunikation / [ed] Jan-Olof Gustafsson, Karlskrona: Högskolan i Karlskrona/Ronneby , 1999Conference paper (Other academic)
  • 11.
    Persson, Patrik
    et al.
    KTH, Superseded Departments, Electromagnetic Theory.
    Josefsson, L
    Calculating the mutual coupling between apertures on a convex circular cylinder using a hybrid UTD-MoM method2001In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 49, no 4, p. 672-677Article in journal (Refereed)
    Abstract [en]

    In this paper, the problem of calculating the mutual coupling between apertures on a perfectly conducting circular cylinder is considered. The mutual coupling is calculated by a combination of uniform theory of diffraction (UTD) and the method of moments (MoM). This hybrid method makes it possible to include higher order aperture modes in order to improve the accuracy. It is found that the UTD-MoM solution gives accurate results, even for small cylinders. The results are verified against results found in the literature, as well as against measurements performed at Ericsson Microwave System in Molndal, Sweden. For this purpose, a cylindrical test antenna with 54 apertures was built. Using a single-mode approximation, good agreement down to about -60 dB, comparisons to measured data has been obtained. If additional modes are added the results improve significantly both in amplitude and phase, Zn several cases, the agreement is good down to coupling levels about -80 dB. This requires that about six modes are included. However, the most important mode, besides the fundamental TE10 mode is the TM11 mode.

  • 12.
    Persson, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Josefsson, L.
    Radiation characteristics of antennas on singly curved surfaces2005Conference paper (Refereed)
  • 13.
    Persson, Patrik
    et al.
    KTH, Superseded Departments, Electromagnetic Theory.
    Josefsson, L
    Lanne, M
    Investigation of the mutual coupling between apertures on doubly curved convex surfaces: Theory and measurements2003In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 51, no 4, p. 682-692Article in journal (Refereed)
    Abstract [en]

    A hybrid method of high-frequency approximation (UTD) and method of moments is used to calculate. the mutual coupling between circular apertures on a doubly curved surface. This requires that the geodesics on doubly curved surfaces be found. To represent the aperture fields, a single waveguide mode approximation is used. In order to verify the theoretical results, a general paraboloid of revolution with circular waveguide-fed apertures was built at Ericsson Microwave Systems AB, Molndal, Sweden. This has given a possibility to verify the theoretical model for a general doubly curved surface against measurements. To the authors' knowledge, no such verification is available in the literature. It was found that measured and theoretical results in terms of mutual coupling agree very well for copolar coupling. As expected, the mutual coupling results are very dependent on the polarization. In fact, the definition of polarization directions and the heed for polarization control are important issues for doubly curved conformal array antennas.

  • 14.
    Persson, Patrik
    et al.
    KTH, Superseded Departments, Electromagnetic Theory.
    Rojas, Roberto G.
    A High Frequency Approximation for Mutual Coupling Calculations between Apertures on a PEC Circular Cylinder Covered with a Dielectric Layer Valid in the Paraxial Region: The Gzz caseManuscript (preprint) (Other academic)
  • 15.
    Persson, Patrik
    et al.
    KTH, Superseded Departments, Electromagnetic Theory.
    Rojas, Roberto G.
    High-frequency approximation for mutual coupling calculations between apertures on a perfect electric conductor circular cylinder covered with a dielectric layer: Nonparaxial region2003In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799X, Vol. 38, no 4, p. 1079-Article in journal (Refereed)
    Abstract [en]

    An asymptotic Green's function technique is presented for the calculation of the surface fields on a perfect electric conductor circular cylinder covered with a dielectric layer. The sources are apertures located on the perfect electric conductor surface. This method is very efficient and valid for large cylinders in terms of wavelengths. The new representation is obtained via Watson's transformation and integral contour deformations. The efficiency of the method results from the circumferentially propagating representation of the Green's function as well as the efficient numerical evaluation of various integrals. Numerical results are presented showing good agreement when compared to other solutions as well as measurements.

  • 16. Volski, V.
    et al.
    Vandenbosch, G.
    Yang, J.
    Kildal, P. -S
    Vipiana, F.
    Pirinoli, P.
    Vecchi, G.
    De Vita, P.
    De Vita, F.
    Freni, A.
    Baccarelli, P.
    Rius, J. M.
    Espinosa, H.
    Mattes, M.
    Valero, A.
    Persson, Patrik
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Sipus, Z.
    Overview of the software integration activities within ACE2006Conference paper (Refereed)
    Abstract [en]

    The ACE project initiated the start of several integration activities between European institutions involved in electromagnetic modeling of antennas with planar or conformal topologies. The goal of the integration activities was / is not to create a global software package that integrates the software of all partners, but to initiate a long term process for antenna software integration activities within the European antenna community. During the first two years of ACE the integration activities were performed in several groups with a rather small number of partners in each group. The groups were formed by partners who wanted to integrate a specific approach developed by one partner into the software code of another partner. This allows increasing the capability and efficiency of a software code. In this paper a short overview of all integration activities is given.

1 - 16 of 16
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